Methods for reducing wear and seizure between rubbing titanium and steel surfaces

ABSTRACT

PROCESSES FOR IMPROVING WEAR AND SEIZURE RESISTANCE BETWEEN HIGH SPEED RUBBING TITANIUM AND STEEL SURFACES BY REACTING THE TITANIUM INITIALLY WITH SODIUM FLUORIDE AT ELEVATED TEMPERATURES OVER AN EXTENDED PERIOD, THE METAL SURFACES BEING LUBRICATED WITH A DIALKYLDITHIOPHOSPHATE.

United States Patent ()fli 3,692,589

Patented Sept. 19, 1972 concentration gradient at or near the titanium surfaces 3,692,589 I which would contact the steel surfaces. The alloying con METHODS FOR REDUCING WEAR ND SEIZURE stituent was commonly a noble metal such as gold or BETVEEN RUBBING TITANIIIM AND STEEL silver, both of which are very costly.

Arfl fi fi gga iro Philadelphia Pa assign to the 5 Other methods were ineffective, unreliable, or could United S'mtespof Amrica'as rerese'lited by Secrb not be adequately reproduced for satisfactory industrial t ry of the Army I pp q N0 Drawing. Filed Nov. 19, 1970, Ser. No. 91,155 It '15 therefore an ob ect of this invention to provide I t, Cl, C23f-1/00 1 improved methods for treating titanium pieces to thus US. Cl. 1486 6 Claims 10 permit their satisfactory use when subjected to rubbing against steel, especially at high speeds.

Other and further objects of the invention will be ap- ABSTRACT OF THE DISCLOSURE parent to those skilled in the art upon study of this dis- Processes for improving wear and seizure resistance closurebetween high speed rubbing titanium and steel surfaces In W l W1th,the abOVePbJCCtF I have Fhscovered by reacting the titanium initially i h' di fluoride at that titanium pieces immersed in sod um fluoride at eleelevated temperatures over an extended period, the metal 7 vated temperatures for extended periods are capable of withstanding high speed rubbing contact with certain steels when appropriate lubricants are used therewith. More specifically, I have discovered that when 75A surfaces being lubricated with a dialkyldithiophosphate.

The invention described herein may be manufacm'red titanium is immersed in NaF at elevated temperatures for used and licensed by or for the Government for governf f q that Wear Selzure resistance of the mental P p without the p y to me of any titanium is remarkably improved when contacting or rubbing 52100 or A181 1137 steels when appropriate y y thereonlubricants are present.

This invention relates to lubricating processes and more particularly concerns methods for improving wear and g f liz g gs fifi g fi jg c iz 2 3 31 4-1Ball seizure resistance between high speed rubbing titanium Engineering v01 136 p ge 46 Q; Se-q oer g and steel surfaces. r

Wear between titanium and Steel Surfaces poses a pap Anti seizure data were obtained using the well-known ncularly Severe lubncanon p obl due m p to the alex Eirtreme Pressure Tester described in Lubrication Engineering, September 1946, V. A. Ryan.

well known fact that titanium readily galls and seizes. "The Falex te t d t d M th d t d t b t v s s were con uc e using aw blocks made 0 S 0 Improve Wear an Selzure reslstance e Ween from A181 1137 steel R 20 and the pin made from 75A these metals have met with limited success and are actitanium The jaw was increased f 0 to 25 companied with attendant disadvantages. For example, 35 pounds by engaging the eccentric arm f the ratchet titan um has been CQat l Wlth fillolildfiphosphate by wheel. When the jaw load reached 250 pounds, the ec- IneISlIlg tltanlum PleCe into a Solutlon thereof- A molyb' centric arm was disengaged and the load maintained for denum disulphide-resin layer was then bound thereto by one minute. Using the same procedure, the jaw load was appropriate heat treatingsteps. The resin most C mm increased in increments of 250 pounds until failure ocly employed was a condensation product of bisphenol A 40 d h i rotated at 290 and epichlorohydrin. The process was costly and time- The 4-Ba1l Wear tests were conducted at 1200 rpm. consuming, requiring a two-layer system. at room temperature. The upper ball was 52100 steel, /2 Another method for reducing wear and seizure ininch in diameter, while the lower balls were A titanium volving titanium pieces required the formation of an alloy of the same diameter. Results of tests are presented below:

ANTI-WEAR AND ANTI-SE12 URE DATA OBTAINED WITH RUBBING Ti AND STEEL SURFACES Test Ti pretreatment Ti treatment Anti-wear data Antiseizure data Al Toluene cleaned None i0 kg. load-1 minute, 2-3 mm. scar. Seized immediately. A2 do b NaF immersion for 5 hours at 50 kg. load-good after 6 hours, test To 2,000 lbs. jaw load.

650 C. halted. A3 d0 b NaF immersion 6 for 3 hours at d0 1,500 lbs. jaw load seized.

540 O. A4 Toluene cleaned, None 10 kg. l0ad1 minute, 2mm. scars Welding and extreme wear on way up to HF pickled. 250 lbs. jaw load-torque erratic. B2 do 4 NzF immersion o for 5 hours at 50hkfi. (load-good after 6 hours, test Seized at 2,500 lbs. jaw load.

50 C a e CrF; immersion Balls destroyed by ClFa. Li?3 ignlr nersion for 5 hours at 454- Balls destroyed by LiF B All tests conducted using 10% by weight zinc dialkyldithiophosphate (50% by weight Ca and 50% by weight Cs), balance 3065 mineral oil, described in Spec. MIL-L-l50ifi8, Amendment 1, dated 10 June 1066, Lubricating 011, General Purpose, mineral oil Except for Approved Pour-Point Depressants and Anti-Foam Agents, 100 centistokes at 75 F.

b Toluene, cleaned by degreasing in toluene.

Titanium piece immersed in a 50 cc. porcelain crucible at room temperature, the crucible then being placed in a cool oven and brought to the stated temperature in about hour. Piece was allowed to cool gradually after being held at the desired temperature.

d Toluene cleaned, and then pickled in a solution containing ml. of 48% HF, 9 ml. concentration HNOQ and the balance water to 1 liter, water washed and dried prior to immersion in NaF.

The zinc dialkyldithiophosphate may contain 100% C to 100% C or any combination of C C and C From the data herein above set forth, it will become evident that the lubricity processes of the present invention improves antiwear and anti-seizure characteristics of 75A titanium pieces when rubbing at high speeds in contact with either 52100 or AISI 1137 steels when a solution of zinc dialkyldithiophosphate (C to C in any proportion) is used as the lubricating agent, the balance being 3065 mineral oil.

I claim: 1. A process for improving wear and seizure resistance between rubbing titanium and steel parts comprising the steps of immersing a cleaned titanium piece in NaF and gradually raising the temperature thereof including said titanium piece to an elevated temperature between about 540 C. and 650 C. to provide a treated piece,

allowing said treated piece to cool to room temperature, and rubbing said cooled piece and said steel parts at high speeds while lubricated with a zinc'dialkyldithiophosphate.

2. The process as described in claim 1 wherein said titanium piece is 75A and said steel is selected from the group consisting of 52100 and A181 1137, said 52100 steel and said AISI 1137 steel having the following compositions:

52100 AISI 1137 C 0. 95-1. 10 032-0. 39 Mn 0. -0. 1. 35-1. 65 P 0. 025 l 0. 045 S 0. 025 Si 0. 20-0. 35 08-0. 13 Cr 1. 20d.

I Maximum.

3. The process as described in claim 1 wherein said phosphate is 10% by weight zinc dialkyldithiophosphate, the alkyl group consisting of C to C in any weight proportion, balance being 3065 mineral oil having the following properties: a

Viscosity, SSU at 210 F. -70 Viscosity index (min.) Pour Point, F. (max) 5 Flash Point, F. (min.) 410 Work Factor (min.) 0.85 Neutralization number (max.) 0.10 Water, percent (max.) a- None Ash, percent (max.) 0.003 Saponification number (max.) 0.50 Nature of carbon (1) Total S, percent (max.) 0.50 Precipitation number (max.) 0.01

1 Loose and fiake'y.

4. ,The process as described in claim 3 wherein said cleaned titanium piece has been degreased in toluene, said elevated temperature is about 650 C. and said extended period is about 5 hours.

5. The process as described in claim 3 wherein said cleaned titanium piece has been degreased in toluene, and

said extended period ranges between about 3 to 5 hours.

6. The process as described in claim 3 wherein said cleaned titanium piece has been degreased in toluene, and then pickled in a hydrofluoric acid solution, and wherein said elevated temperature is about 650 C. and said extended period is about 5 hours.

References Cited UNITED STATES PATENTS 2,328,933 9/1943 Streicher 14820 3,041,215 6/1962 Jenkins et al 1486.l4 R 2,554,042 5/1951 Mayfield 14820 X 3,158,515 11/ 1964 Miclael 14820 2,844,499 7/1958 Wainer 148-20 2,838,430 6/1958 Argcnta.

OTHER REFERENCES Shapiro, ASLE Transactions 12(1), 1969, pp. -85.

RALPH S. KENDALL, Primary Examiner U.S. Cl. X.R. 

